Although cancer treatment-related fatigue (CRF) is recognized as the most common side effect of cancer treatment, the scientific basis for its management is extremely limited. This randomized controlled clinical trial tests a telephone based energy conservation/activity management (ECAM) intervention with regard to its effects o perceived level of fatigue and selected domains of quality of life (level of functioning and negative mood). A secondary aim is to examine the relationship of other side effects and symptoms to CRF. The study is guided by the Common Sense Model of illness. Patients beginning treatment for lung, breast, and colorectal cancer will be randomized to an ECAM intervention or attentional control group. The ECAM includes information, coping skills training, and evaluation components that are consistent with the Common Sense Model as well as previous research testing psychoeducational interventions with cancer patients. Participants in the ECAM group will receive three telephone counseling sessions delivered by specially trained oncology nurses. Timing of the intervention is tied to the onset of fatigue for each type of treatment. Individuals having chemotherapy (CTX) receive the intervention during weeks 1, 2, and 3 of the treatment cycle while those having radiation therapy (RT) receive the intervention during weeks 3, 4, and 5 of treatment. The primary outcomes - perception of fatigue, limitation of functioning, and negative mood - will be measured prior to first treatment (baseline) for all participants. Those receiving CTX complete follow-up measures 48 hours after the second cycle and 48 hours before the third cycle of treatment, expected times of high and low fatigue. Those receiving RT complete follow-up measures during the sixth week of treatment and one month after the completion of treatment, times of high and low fatigue. Data will be analyzed using multivariate repeated measures analysis of covariance. The findings of this study will contribute to the scientific basis for oncology nursing practice for CRF management.